Semaphore o Synchronization tool that does not require busy waiting o Semaphore S-integer variable o Two standard operations modify S:acquire0 and release( Originally called PO and VO o Less complicated o Can only be accessed via two indivisible(atomic)operations acquire(){ while value <=0 ;/no-op value--; release(){ value++;Semaphore  Synchronization tool that does not require busy waiting  Semaphore S – integer variable  Two standard operations modify S: acquire() and release()  Originally called P() and V()  Less complicated  Can only be accessed via two indivisible (atomic) operations